PHP generates N non-repeating random number example code

This article mainly describes how to use php to generate N non-repeating random number instances. The code is as follows:

<?php
/*
* array unique_rand( int $min, int $max, int $num )
* 生成一定数量的不重复随机数
* $min 和 $max: 指定随机数的范围
* $num: 指定生成数量
*/
function unique_rand($min, $max, $num) {
    $count = 0;
    $return = array();
    while ($count < $num) {
        $return[] = mt_rand($min, $max);
        $return = array_flip(array_flip($return));
        $count = count($return);
    }
    shuffle($return);
    return $return;
}
$arr = unique_rand(1, 25, 16);
sort($arr);
$result = &#39;&#39;;
for($i=0; $i < count($arr);$i++)
{
 $result .= $arr[$i].&#39;,&#39;;
}
$result = substr($result, 0, -1);
echo $result;
?>

The program runs as follows:

The code is as follows:

2,3,4,6,7,8,9,10,11,12,13,16,20,21,22,24

Additional remarks:
The mt_rand() function is used to generate random numbers. This function generates random numbers four times faster on average than rand().
When removing duplicate values ​​from the array, the "flip method" is used, which is to use array_flip() to exchange the key and value of the array twice. This approach is much faster than using array_unique().
Before returning the array, first use shuffle() to assign new key names to the array, ensuring that the key names are consecutive numbers from 0-n. If this step is not performed, the key names may be discontinuous when deleting duplicate values, causing trouble in traversal.

The above is the detailed content of PHP generates N non-repeating random number example code. For more information, please follow other related articles on the PHP Chinese website!